1. Field of the Invention
The present invention relates generally to electrochemical energy storage devices and systems. In particular, the invention relates to a flow battery system.
2. Description of Related Art
To enable the widespread use of renewable electric energy (e.g., solar and wind) there is a critical need for a cost effective grid scale energy storage solution that is independent of the geological and ecological landscape. Today, pumped hydro and sub-surface compressed air, while economically viable, are generally recognized as unsuitable for widespread deployment, and existing battery technologies are either too expensive or unreliable.
The Li/S battery has been the subject of considerable work to date, typically aimed at creating high energy density batteries chiefly for mobile/portable applications. Generally composed of a lithium metal anode, a sulfur cathode, and a polysulfide electrolyte, the Li/S battery is regarded for its high specific energy and low raw materials cost, but is also considered unexceptional in its ability to cycle. Corrosion of lithium metal in direct contact with the polysulfide electrolyte is one of the major factors leading to its poor cycling efficiency, and in certain applications this also brings about an unacceptably high self-discharge rate.
Today there exists a critical need for a cost effective grid scale battery storage solution, where the key technology driver is battery service life, and ultimately cost. Sulfur is inexpensive, but previously known sulfur-based batteries (e.g., Li/S) are unsuitable or otherwise have not yet achieved performance inline with the needs of the utility grid.